Rack power distribution unit with detachable cables

ABSTRACT

A system includes a rack, computing devices coupled to the rack, a rack PDU, and one or more input power cables. The rack PDU includes an enclosure, two or more power input receptacles on the enclosure, and two or more power output receptacles on the enclosure. The output power receptacles supply power to the computing devices. The input power cables are coupled in one or more of the power input receptacles. The input power cables supply electrical power from an electrical power system to the rack PDU.

This application is a continuation of U.S. patent application Ser. No.13/560,653, filed Jul. 27, 2012, now U.S. Pat. No. 8,902,569.

BACKGROUND

Organizations such as on-line retailers, Internet service providers,search providers, financial institutions, universities, and othercomputing-intensive organizations often conduct computer operations fromlarge scale computing facilities. Such computing facilities house andaccommodate a large amount of server, network, and computer equipment toprocess, store, and exchange data as needed to carry out anorganization's operations. Typically, a computer room of a computingfacility includes many server racks. Each server rack, in turn, includesmany servers and associated computer equipment.

Because the computer room of a computing facility may contain a largenumber of servers, a large amount of electrical power may be required tooperate the facility. In addition, the electrical power is distributedto a large number of locations spread throughout the computer room(e.g., many racks spaced from one another, and many servers in eachrack). Usually, a facility receives a power feed at a relatively highvoltage. This power feed is stepped down to a lower voltage (e.g.,110V). A network of cabling, bus bars, power connectors, and powerdistribution units, is used to deliver the power at the lower voltage tonumerous specific components in the facility.

In some computer systems, one or more rack-level power distributionunits are provided in a rack to distribute electrical power to the manyservers in the rack. Each of the rack-level power distribution units mayinclude a case with a large number of receptacles, each of which may beused to supply power to a different server, and a built-in input powercable that passes out of the case. Rack-level power distribution unitsmay be attached to one or both interior sides of the rack near one endof the rack.

In some facilities, power is supplied to racks either through the topsof the racks or the bottoms of the racks. For example, power may be fedthrough the bottom of a rack from floor power distribution units orpower panels under a false floor in a room of the data center. In somecases, rack PDUs are pre-installed in rack before the rack is placed inthe data center. If the input power cable for the rack PDU is orientedin the wrong direction (for example, extending from the top of the rackPDU of a data center where power is fed from the bottoms of the racks),routing and cable management may be significantly more difficult (forexample, longer cable runs, more cable bends, and morecrossing/interweaving of input cables with other cables). In some cases,the rack PDU may be removed and the orientation reversed (inverting topwith bottom, for example) to improve routing. Removing and reorientingrack PDUs may, however, be laborious (and thus add to installationcosts), especially if the process must be repeated for many racks.

From time to time, rack PDUs operating in a data center may fail andneed to be replaced. Removing a rack PDU may involve disconnecting apower input cable from a power source and feeding the power input cableinto the rack (for example, through the bottom of the rack and falsefloor). Installing the replacement rack PDU may involve feeding the newpower input cable back through and connecting to the power source.

Primary power systems for computer systems in operation typically needto be maintained or reconfigured from time to time. Some data centers,for example, have “single threaded” distribution via the electricalpower supply to the floor and/or to the rack, and in which maintenancecan only be performed when the components using power in the datacenter, such as servers, are shut-off. The down-time associated withmaintenance and reconfiguration of primary power systems in a datacenter may result in a significant loss in computing resources. In somecritical systems such as hospital equipment and security systems,down-time may result in significant disruption and, in some cases,adversely affect health and safety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating one embodiment of a powerdistribution system including rack power distribution units withmultiple power input receptacles.

FIG. 2 illustrates one embodiment of a data center including rack powerdistribution units with dual power input receptacles and detachablepower cables.

FIG. 3 illustrates one embodiment of a rack power distribution unit witha phase match detection system with visual match indicators.

FIG. 4 illustrates one embodiment of a rack power distribution unit witha phase match detection system with control among multiple power inputs.

FIG. 5 illustrates one embodiment of a secondary feed to a rack powerdistribution unit.

FIG. 6 illustrates one embodiment of multiple data centers withdifferent rack PDU power cables for different source power panels.

FIG. 7 illustrates one embodiment of connecting power to a rack powerdistribution unit with multiple power input receptacles.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexample in the drawings and will herein be described in detail. Itshould be understood, however, that the drawings and detaileddescription thereto are not intended to limit the invention to theparticular form disclosed, but on the contrary, the intention is tocover all modifications, equivalents and alternatives falling within thespirit and scope of the present invention as defined by the appendedclaims. The headings used herein are for organizational purposes onlyand are not meant to be used to limit the scope of the description orthe claims. As used throughout this application, the word “may” is usedin a permissive sense (i.e., meaning having the potential to), ratherthan the mandatory sense (i.e., meaning must). Similarly, the words“include,” “including,” and “includes” mean including, but not limitedto.

DETAILED DESCRIPTION OF EMBODIMENTS

Various embodiments of rack power distribution units, and methods ofimplementing and maintaining systems using rack power distributionunits, are disclosed. According to one embodiment, a system includes arack, computing devices coupled to the rack, a rack PDU, and one or moreinput power cables. The rack PDU includes an enclosure, two or morepower input receptacles on the enclosure, and two or more power outputreceptacles on the enclosure (for example, one power input receptaclenear the top of the enclosure and another power input receptacle nearthe bottom of the enclosure). The output power receptacles supply powerto the computing devices. The input power cables are coupled in one ormore of the power input receptacles. The input power cables supplyelectrical power from an electrical power system to the rack PDU.

According to one embodiment, a rack power distribution unit (PDU)includes an enclosure, two or more power input receptacles on theenclosure, and two or more power output receptacles on the enclosure.The power input receptacles are wired in parallel with one another. Thepower output receptacles supply power to electrical systems.

According to on embodiment, a method includes providing a rack powerdistribution unit (PDU) with two or more rack PDU input powerreceptacles, and coupling a power cable to one or more of the rack PDUinput power receptacles.

As used herein, a “cable” includes any cable, conduit, or line thatcarries one or more conductors and that is flexible over at least aportion of its length. A cable may include a connector portion, such asa plug, at one or more of its ends.

As used herein, “computing” includes any operations that can beperformed by a computer, such as computation, data storage, dataretrieval, or communications.

As used herein, “computing device” includes any of various devices inwhich computing operations can be carried out, such as computer systemsor components thereof. One example of a computing device is arack-mounted server. As used herein, the term computing device is notlimited to just those integrated circuits referred to in the art as acomputer, but broadly refers to a processor, a server, amicrocontroller, a microcomputer, a programmable logic controller (PLC),an application specific integrated circuit, and other programmablecircuits, and these terms are used interchangeably herein. Some examplesof computing devices include e-commerce servers, network devices,telecommunications equipment, medical equipment, electrical powermanagement and control devices, and professional audio equipment(digital, analog, or combinations thereof). In various embodiments,memory may include, but is not limited to, a computer-readable medium,such as a random access memory (RAM). Alternatively, a compact disc-readonly memory (CD-ROM), a magneto-optical disk (MOD), and/or a digitalversatile disc (DVD) may also be used. Also, additional input channelsmay include computer peripherals associated with an operator interfacesuch as a mouse and a keyboard. Alternatively, other computerperipherals may also be used that may include, for example, a scanner.Furthermore, in the some embodiments, additional output channels mayinclude an operator interface monitor and/or a printer.

As used herein, “computer room” means a room of a building in whichcomputer systems, such as rack-mounted servers, are operated.

As used herein, “data center” includes any facility or portion of afacility in which computer operations are carried out. A data center mayinclude servers dedicated to specific functions or serving multiplefunctions. Examples of computer operations include informationprocessing, communications, simulations, and operational control.

As used herein, one component in a power distribution system is“downstream” from another component in the power distribution system ifthe one component receives power from the other component or is at alower level in the power distribution system than the other component.For example, a floor PDU may be downstream from a UPS, or a power supplyunit in a server may be downstream from a rack PDU.

As used herein “floor-level”, as applied to a component or system, meansthe component or system serves two or more racks on the floor of acomputer room or other facility.

As used herein, “floor power distribution unit” refers to a powerdistribution unit that can distribute electrical power to variouscomponents in a computer room. In certain embodiments, a floor powerdistribution unit includes a transformer. In one embodiment, a floorpower distribution unit includes a k-rated transformer. A powerdistribution unit may be housed in an enclosure, such as a cabinet.

As used herein, a “match”, in the context of matching sets of powerlines, means that the characteristics between the sets of power linesare similar to one another within acceptable limits. A match does notrequire that the measurements of the two items be precisely equal. Insome embodiments, the acceptable variance levels for a match arepredetermined. For example, in one embodiment, for a voltage levelmatch, an input power line may be predetermined to match a feed line ifthe difference in measured voltage between the two lines is 7 volts orless. Various characteristics, such as voltage, waveform, etc. may beused as criteria to determine a match.

As used herein, a “module” is a component or a combination of componentsphysically coupled to one another. A module may include functionalelements and systems, such as computer systems, circuit boards, racks,blowers, ducts, and power distribution units, as well as structuralelements, such a base, frame, housing, or container.

As used herein “PDU-level”, as applied to a component or system, meansthe component or system serves a single PDU, or electrical systemscoupled to a single PDU.

As used herein, “power distribution unit” means any device, module,component, or combination thereof, that can be used to distributeelectrical power. The elements of a power distribution unit may beembodied within a single component or assembly (such as a transformerand a rack power distribution unit housed in a common enclosure), or maybe distributed among two or more components or assemblies (such as atransformer and a rack power distribution unit each housed in separateenclosure, and associated cables, etc.). A power distribution unit mayinclude a transformer, power monitoring, fault detection, isolation.

As used herein, “power panel” means any panel, device, module,component, or combination thereof, that can be used to transfer ordistribute electrical power from one or more input conductors to one ormore output conductors. In certain embodiments, a remote power panelincludes main lug only panel conductors. A remote power panel may behoused in an enclosure, such as a cabinet.

As used herein, “primary power” means any power that can be supplied toan electrical load, for example, during normal operating conditions.

As used herein, a “rack” means a rack, container, frame, or otherelement or combination of elements that can contain or physicallysupport one or more computing devices.

As used herein, a “rack computing system” means a computing system thatincludes one or more computing devices mounted in a rack.

As used herein “rack-level”, as applied to a component or system, meansthe component or system serves electrical systems in a particular rack.

As used herein, “rack power distribution unit” refers to a powerdistribution unit that can be used to distribute electrical power tovarious components in a rack. A rack power distribution may includevarious components and elements, including wiring, bus bars, connectors,and circuit breakers. In some embodiments, a rack power distributionunit may distribute power to only some of the electrical systems in arack. In some embodiments, a single rack includes two or more rack powerdistribution units that distribute power to different sets of electricalsystems in the rack. For example, one rack may include a left rack powerdistribution unit that distributes power to half of the servers in therack, and a right rack power distribution unit that distributes power tothe other half of the servers in the rack.

As used herein, “reserve power” means power that can be supplied to anelectrical load upon the failure of, or as a substitute for, primarypower to the load.

As used herein, a “secondary feed” refers to any feed that suppliespower that is separate from a primary power system for at least aportion of a primary power chain. As used herein, a “tertiary feed”refers to any feed that supplies power that is separate from two powersystems (such as a primary power system and a reserve power system) forat least a portion of the two power system chains. In some embodiments,a secondary power feed or tertiary feed may be completely independent ofthe primary power distribution system. In some embodiments, however, asecondary feed or tertiary feed is not completely independent of theprimary power distribution system. For example, both the primary powerdistribution system and a secondary feed may both receive power from thesame utility feed, the same step-down transformer (for example, aprimary-side transformer), the same uninterruptible power supply (forexample, a primary-side), etc.

As used herein, one component in a power distribution system is“upstream” from another component in the power distribution system ifthe one component supplies power to the other component or is at ahigher level in the power distribution system than the other component.For example, a UPS may be upstream from a floor PDU, or a rack PDU maybe upstream from a power supply unit for a server.

In some embodiments, a system includes racks that hold computing devicesfed by a rack PDU with multiple power input receptacles. The multiplepower input receptacles may allow for connecting power at multiplelocations on the rack PDU. In one embodiment, one of the power inputreceptacles may be near the top of the rack PDU, and another of thepower input receptacles is near the bottom of the rack PDU. A powercable may be coupled to one or both of the input receptacles. The powercable may supply power to the computing devices through the rack PDU.

FIG. 1 is a block diagram illustrating one embodiment of a powerdistribution system including rack power distribution units withmultiple power input receptacles. System 100 includes power distributionsystem 102 and electrical systems 104. In one embodiment, system 100 isa data center. Electrical systems 104 may include, for example,computing devices, rack-mounted servers, network control devices, powersupply units, air moving devices, and mass storage devices. Electricalsystems 104 may be supported in racks 106. Electrical systems 104 mayperform various functions in a data center, such as data storage ornetwork services. In one embodiment, electrical systems 104 are serversin a server room of a data center.

Each of electrical systems 104 may include a power supply unit. Thepower supply unit may supply power to various electrical components,such as integrated circuits, central processing units, solid statememory, and hard disk drives in electrical systems 104.

Power distribution system 102 includes transformer 110, generators 112,switchgear apparatus 114, and primary power systems 116. Each of primarypower systems 116 includes UPS 118 and one or more power panels 120.

Electrical systems 104 in racks 106 may each receive power from one ofprimary power systems 116. In one embodiment, each of primary powersystems 116 corresponds to, and provides power to, the servers in oneroom in a data center. In one embodiment, each of primary power systems116 corresponds to, and provides power to, one rack system in a datacenter. In FIG. 1, for the sake of clarity, electrical systems 104 areshown coupled to only one of power panels 120. Electrical systems may,however, be coupled to any or all of power panels 120 in a data center.

Power panels 120 may distribute power from UPSs to electrical systems104 in racks 106. Power panels 120 may include circuit protectiondevices, such as circuit breakers. In certain embodiments, power panels120 are floor power distribution units. In some embodiments, some or allof power panels 120 include a transformer that transforms the voltagefrom switchgear apparatus 114.

Power panels 120 include circuit protection devices 124. Circuitprotection devices 124 may operate to shed loads from electrical systems104 off of power distribution system 102. Circuit protection devices 124may be triggered to shed loads on a load circuit-by-load circuit basis.For example, a circuit breaker may shed loads from computing devicesoperating in a particular rack, or computing devices in a particularhalf of a rack (for example, top half and bottom half).

In some embodiments, loads are shed by tripping circuit breakers inpower panels 120. Loads may be shed by tripping breakers correspondingto, for example, computing devices in a full rack or in half of a rack.

Each of racks 106 may include one or more rack power distribution units122. The rack power distribution units 122 may distribute power to powersupply units in computer systems 104. In one embodiment, each rack powerdistribution units 122 distributes electrical power to half of a rack.

Each of rack PDUs 122 includes two power input receptacles 123. Eitherpower input receptacles 123 may be coupled to a detachable power supplycable that carries power from power panels 120 to the rack PDU.

Each of rack PDUs includes two branches 125. Each of the two branchesmay include a set of output power receptacles. In operation of system100, receptacles in rack PDU 122 may be used to supply power toelectrical systems in rack 106, such as servers. Electrical systems 104may be coupled to rack power distribution unit 122 by way of cables.

Each of branches 125 in rack PDU 122 includes circuit protection devices128. Circuit protection devices may be, for example, circuit breakers orfuses. In one embodiment, each breaker is a 30A/32A single pole MCB.Breakers may be located such that they can be accessed when server racksare in-line (e.g., at the top of rack power distribution unit 122). Inone embodiment, power is provided to a rack PDU by way of an 8AWG/6 mm²5 core cable and a 30A NEMA/32A IEC309 3Ph+N+E Plug.

In the schematic diagram shown in FIG. 1, for purposes of clarity, eachof circuit protection devices 124 is represented by a box having asingle symbol. A circuit protection device may, however, include anynumber of separate devices. For example, a separate device may beprovided for each line of a power distribution circuit. In oneembodiment, for instance, separate devices (for example, circuitbreakers) are provided for hot and neutral. In another embodiment,separate devices are provided for each phase line of a multi-phase powerdistribution system.

Although in the system shown in FIG. 1, each of the rack PDUs has twobranches, a rack PDU may, in various embodiments, have any number ofbranches and any number of circuit protection devices.

In FIG. 1, circuit protection devices are provided in power panels andrack power distribution units that feed electrical systems in racks 106.Circuit protection devices may, nevertheless, be included in otherlevels and locations in a power distribution system. For example, UPSs118 or switch gear 114 may include circuit protection devices.

In some embodiments, electrical systems, or sets of electrical systems,are assigned one or more identifiers. In some embodiments, powercomponents in a power distribution system, such as power panels, areassigned one or more identifiers. Each identifier may serve as anaddress for the electrical system, rack system, power component, or aconstituent element thereof. The address may be used to map loads (suchas server racks) and power components in a system. An identifier mayhave any suitable format. In some embodiments, a separate identifier maybe assigned for the component itself and for additional elements,inputs, or outputs within the component. For example, a separateidentifier may be established for each power output receptacle of apower panel.

Transformer 110 is coupled to a utility feed. The utility feed may be amedium voltage feed. In certain embodiments, the utility feed is at avoltage of about 13.5 kilovolts or 12.8 kilovolts at a frequency ofabout 60 Hz. Generators 104 may provide power to primary power systems106 in the event of a failure of utility power to transformer 110. Inone embodiment, one of generators 112 provides back-up power for each ofprimary power systems 116.

UPS 118 may provide uninterrupted power to racks 106 in the event of apower failure upstream from UPS 118. In certain embodiments, a UPSreceives three-phase power from a transformer. The UPS may supplythree-phase power to a floor power distribution unit.

PDU power may be any suitable voltage. In one embodiment, electricalpower is about 208 V. In one embodiment, electrical power is about 230V. In some embodiments, different electrical systems 104 may operate ondifferent phases of a primary power system. Each of the legs maycorrespond to one phase of the input power. In one embodiment, each legoperates at a voltage between about 220 volts to about 260 volts.

Reserve power system 130 may provide reserve power for any or all of theelectrical systems 104 supplied by primary power systems 116. In someembodiments, reserve power system 130 is powered up at all times duringoperation of system 100. Reserve power system 130 may be passive until afailure of one or more components of the primary power system for one ormore of electrical systems 104, at which time reserve power system 130may become active.

For illustrative purposes, three switchgear apparatus 114, four UPSs118, and ten power panels 120 are shown in FIG. 1. The number of powerdistribution units, UPSs, switchgear apparatus may, however, vary fromembodiment to embodiment (and, within a given embodiment, from system tosystem). For example, each of UPSs 118 may supply power to any suitablenumber of power panels 120. As another example, each of switchgearapparatus 114 may supply power to any suitable number of UPSs 118.

In some embodiments, a map is generated for electrical systems (forexample, servers) that perform operations in a facility, powercomponents in a power distribution system, or both. The map may be basedon signals sent from various components in a data center. For example,in the embodiment shown in FIG. 1, a map can be established thatincludes sets of electrical systems 104 in racks 106 (for example,servers in one half of a particular rack), rack PDUs 122, power panels120, and UPSs 118.

In some embodiments, computing assets are mapped to one or more powerdistribution system components and/or branches. Mapping may be based onIDs assigned to one or more assets, or sets of assets, of a system. Inone embodiment, sets of computing devices operating in racks are mappedto circuit breakers that provide overcurrent protection for that set ofcomputing devices. For example, Servers ID0001 through 0010 in Rack 0006in Data Center 4 may be mapped to Circuit Breaker A021 in Power PanelPP062 in Data Center 4; Servers ID0011 through 0020 in Rack 0007 of DataCenter 4 may be mapped to Circuit Breaker A022 in Power Panel PP062 inData Center 4; etc.

In some embodiments, baseline data for mapping of components one or morea computing facilities are stored in a database. At a later time, themap may be updated based on a new set of messages from components in thecomputing facilities. Comparisons between the baseline data and currentdata may be used to assess conditions or components.

Electrical systems supplied by power by way of rack power distributionunits may be of various types. Examples include hospital equipment,utility systems, security systems, military systems, telecommunicationssystems, or electronic commerce systems. In certain embodiments, rackpower distribution units supply power to a critical system, such as alife support system. In some embodiments, the systems are computingdevices (for example, servers) in a data center.

FIG. 2 illustrates one embodiment of a data center including rack powerdistribution units with dual power input receptacles and detachablepower cables. System 140 includes rack computing systems 142 and powersystems 144. Each of rack computing systems includes rack 146, computingdevices 148, and rack PDUs 150. Rack PDUs distribute power from powersystems 144 to computing devices 148 installed in racks 146.

Power systems 144 include UPS 156 and floor power distribution units158. Each of floor power distribution units 158 includes floor PDUreceptacles 160. In some embodiments, power system 144 may be similar tothat described above relative to FIG. 1. For example, power system 144may include a network of switchgear apparatus, UPSs, and powerdistribution units that distribute electrical power to any number ofelectrical systems, such as computing devices 148.

Each of rack PDUs 150 includes banks of output receptacles 171 and 172and circuit protection devices 173 and 174. The set of computing devices142 that is coupled in output receptacles 171 may be protected bycircuit protection device 172. The set of computing devices 142 that iscoupled in output receptacles 173 may be protected by circuit protectiondevice 174. In one embodiment, each of circuit protection devices 172and 174 are circuit breakers. In one embodiment, each of banks 171 and173 includes two or more C19-type output receptacles and two or moreC13-type output receptacles.

Each of rack PDUs 150 includes top power input receptacle 180 a andbottom power input receptacle 180 b. Top power input receptacle 180 aand bottom power input receptacle 180 b may be provided on enclosure188. Enclosure 188 may be, for example, a metal case. As used herein, areceptacle is a “top” receptacle of a device if the receptacle is nearerto the top of the device than the bottom of the device. As used herein,a receptacle is a “bottom” receptacle of a device if the receptacle isnearer to the bottom of the device than the top of the device. Each ofthe conductors in top power input receptacle 180 a may be coupled to acorresponding conductor of a bottom power input receptacle 180 b (forexample, hot 180 a to hot 180 b, neutral 180 a to neutral 180 b, and soon.) Power through either of top power input receptacle 180 a and bottompower input receptacle 180 b may be fed through either or both of bank171 and bank 172 of output receptacles.

Power cables 190 and 192 may be installed between one of the power inputreceptacles on rack PDU (either top power input receptacle 180 a andbottom power input receptacle 180 b) and one of floor PDU receptacles160 on floor power distribution unit 158. In certain embodiments, powercables are fed through a floor or ceiling of a room in a data center,such as false floor 194.

Each of power cables 190 and 192 may include a connector plug thatcouples in one of the power input receptacles in rack PDUs 150. In oneembodiment, input connector plugs 196 are L6-30P type plugs and powerinput receptacles 180 a and 180 b are L6-30R type receptacles.

In some embodiments, a power cable includes a Y such that the cable canbe connected to two or more rack PDU power input receptacles (such as,for example power cable 192 shown in FIG. 2). In other embodiments, apower cable has a single connector at each of two ends (such as, forexample, power cables 190 shown in FIG. 2).

In some embodiments, power cables are fed to the rack PDU power inputreceptacle that is nearest to the location of the feed. For example, ifa power cable is fed through the top of the rack, then the power cablemay be coupled in the top power input receptacle of the rack PDU.

In some embodiments, all of the rack PDUs in a particular rack aresupplied with power through either the top or the bottom of the rack andcoupled to power input receptacles on that end of the rack. For example,in the middle rack shown in FIG. 2, both of cables 190 are fed throughthe top of the rack and coupled to one of top power input receptacles180 a. In certain embodiments, one or more of the rack PDUs are fed fromthe bottom of a rack and one or more rack PDUs are fed from the top ofthe same rack.

Suitable types of circuit breakers may include, in various embodiments,a thermal-magnetic circuit breaker, a magnetic circuit breaker, amechanical circuit breaker, or an electronic circuit breaker.

FIG. 3 illustrates one embodiment of a rack power distribution unit witha phase match detection system with visual match indicators. System 200includes rack 146, computing devices 148, and rack PDU 202. Rack PDU 202includes phase match detection device 204, visual indicator panel 206,and circuit breakers 210. Visual indicator panel 206 may includeindicator lamps 208. Circuit breakers 210 may be manually operable by auser to switch power off from either or both of power input receptacles180 a and 180 b.

Phase match detection device 204 may compare input power lines coupledto power input receptacle 180 a with input power lines coupled to powerinput receptacle 180 b. Phase match detection device 204 may include acontrol circuit (which may include, for example, a programmable logiccontroller) that determines whether a phase match exists between powerconnected to the power input receptacles. In some embodiments, phasematch detection device 204 includes one or more voltage comparators.

Phase match detection device 204 may control indicator lamps 208 onindicator panel 206. Indicator panel 206 may provide maintenancepersonnel with information about conditions and connections in rack PDU202.

In some embodiments, indicator panel 206 provides a visual indication ofwhether a phase match exists between power lines connected to the powerinput receptacle 180 a and power input receptacle 180 b. For example,the phases of power to the two input receptacles matches, a green lightmay be illuminated. If the phases of the power to the two inputreceptacles do not match, a red light may be illuminated. Otherinformation that may be presented on a rack PDU indicator panel mayinclude, in various embodiments, power on/off for each input (forexample, power input receptacle 180 a and power input receptacle 180 b),load connected yes/no, input power lines coupled to each other yes/no.

In some embodiments, a rack PDU may provide for a lockout of power ifphases of the inputs do not match. For example, in rack PDU 202 shown inFIG. 3, if phase match detection device 204 determines that the phasesof power introduced at power input receptacle 180 a and power inputreceptacle 180 b does not match, phase match detection device 204 mayoperate shunt devices 212 to trip one or more of circuit breakers 210 toisolate the two power inputs from one another.

In some embodiments, indicator panel 206 includes a screen display. Incertain embodiments, in certain embodiments a panel on a rack PDU allowsa user to input instructions, change settings, change a display, orotherwise control a phase match detection system.

In some embodiments, a rack PDU includes a switching circuit to controlconnections among multiple outputs and multiple inputs. FIG. 4illustrates one embodiment of a rack power distribution unit with aphase match detection system with control among multiple power inputs.System 220 includes rack 146, computing devices 148, and rack PDU 222.Rack PDU 222 includes phase match detection device 204, visual indicatorpanel 206, and switching devices 230.

Phase match detection device 204 may compare input power lines coupledto power input receptacle 180 a with input power lines coupled to powerinput receptacle 180 b. Phase match detection device 204 may include acontrol circuit (which may include, for example, a programmable logiccontroller) that determines whether a phase match exists between powerconnected to the power input receptacles. In some embodiments, phasematch detection device 204 includes one or more voltage comparators.

Phase match detection device 204 may operate switching devices 230 tocontrol connections among power inputs from power input receptacles 180a, 180 b, and output receptacles 171 and 172. Switching devices 230 mayinclude, for example, a set of relays that open and close a connectionthe input power lines. In one embodiment, phase match detection device204 does not allow the input power lines from power input receptacles180 a and 180 b to be connected to each other unless a phase matchexists between the two input power lines.

In some embodiments, maintenance or reconfiguration operations areperformed under live conditions while electrical systems remain inoperation as power is supplied through a secondary feed (for example,while maintaining servers in a powered up state and performing computingoperations using the servers). For example, computer systems in a rackare maintained live while an automatic transfer switch between a floorpower distribution unit and a source power panel is replaced. Thereplacement may be carried out in a “live” environment in which thecomputer systems in the rack remain in operation.

In some embodiments, a secondary feed is supplied to a rack PDU througha power input receptacle on the rack PDU. FIG. 5 illustrates oneembodiment of a secondary feed to a rack power distribution unit througha power input receptacle. System 260 includes rack computing systems262, primary power system 264, and secondary power system 266. Incertain embodiments, secondary power system 266 is a reserve powersystem. Rack computing system 262 includes rack 146, computing devices148, and rack PDU 268. Rack PDU 268 may be similar to rack PDU 202described above relative to FIG. 3, or rack PDU 222 described aboverelative to FIG. 4.

Initially, rack PDU 268 may be coupled only to primary power system 264by way of power cable 270 coupled to power input receptacle 180 a. Toestablish a secondary feed, power cable 272 may be used to couplesecondary power system with rack PDU 268 via power input receptacle 180b. Before cutting in the secondary feed from secondary power system 266,phase match detection device 270 may be used to ensure that a phasematch exists between the power coming into power input receptacle 180 aand power input receptacle 180 b.

In some embodiments, a rack PDU system includes two or more detachablecables. Each of the cables may have a different combination of connectorplugs. Each of the cables may be used to connect the rack PDU to powersources with different output connections. FIG. 6 illustrates oneembodiment of multiple data centers with different rack PDU power cablesfor different source power panels. Data center room 300 both includerack computing systems 304 with rack PDUs 305. Rack computing systems304 and rack PDUs 305 may be identical in both of data center rooms 300and data center rooms 302.

Data center room 300 includes power panel 306 with power panelreceptacles 310. Data center room 302 includes power panel 308 withpower panel receptacles 312. Power panel receptacles 310 in data centerroom 300 and power panel receptacles 312 in data center room 302 may beof different connector types. For example, power panel receptacles 310may NEMA L6-30R type, while power panel receptacles 312 are an IEC309-type receptacle. Cable 314 includes connector plug 316 and connectorplug 318. Cable 320 includes connector plug 316 and connector plug 318.Connector plug 316 and connector plug 318 of cable 314 may both be NEMAL6-30P type. Cable 320, by contrast, may include a NEMA L6-30P typeconnector plug at one end (connector plug 318) and an IEC 309-typeconnector plug at the other end (connector plug 322). Since plug 318 isthe same connector type in both of cable 314 and cable 320, both cablescan interchangeably couple with power input receptacles 317 of rack PDUs305.

In some embodiments, configuring or reconfiguring a system includeconnecting a power source to an input receptacle of a rack PDU. FIG. 7illustrates one embodiment of connecting power to a rack powerdistribution unit with multiple power input receptacles. At 400, a rackpower distribution unit (PDU) with two or more rack PDU input powerreceptacles is provided. The rack PDU may include a top input powerreceptacle and a bottom input power receptacle.

At 402, a power cable is coupled to one or more of the rack PDU inputpower receptacles. The power cable may be coupled to the power inputreceptacle of the rack PDU that is nearest to a feed location of thepower cable into the rack.

In some embodiments, the power source to computing devices in a rack maybe switched by installing a cable in one input receptacle (thereplacement power input) and then removing a cable from another input(the replaced input). The transfer may be carried out while computingdevices in the rack remain in operation.

In some embodiments, a power cable is connected to an input powerreceptacle to establish a secondary feed, such as described aboverelative to FIG. 5. Establishing a secondary feed may include verifyinga phase match between a primary feed into one input power receptacle anda secondary feed into another input power receptacle.

In certain embodiments, a power supply cable is switched from one powerinput receptacle on a rack PDU to another input receptacle on the rackPDU. The cable may be switched for example, to facilitate reroutingcables or eliminating crossing of cables.

In some embodiments, removing and replacing a rack PDU include. A rackPDU may be replaced, for example, if the rack PDU is faulty. Replacementof a rack PDU may include disconnecting the power cable from a failedrack PDU, removing the failed rack PDU from the rack, installing areplacement rack PDU, and connecting the power cable to at least onepower input receptacle of the second rack PDU.

Although in many of the embodiments described herein, rack PDUs aredescribed for use in rack computing systems in a data center, rack PDUsmay, in various embodiments, be used to supply power to other types ofelectrical systems. For example, rack PDUs may be used to distributepower to electrical systems at a power plant, manufacturing plant,medical care facility, or office building.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. A system, comprising: a rack; one or morecomputing devices coupled to the rack; one or more rack powerdistribution units (PDUs) coupled to the rack, wherein at least one ofthe one or more rack PDUs comprises: an enclosure; two or more powerinput receptacles mounted on the enclosure, at least two of the two ormore power input receptacles are wired in parallel with one another,wherein: at least one of the two or more power input receptacles is atop power input receptacle mounted on a top portion of the enclosure;and at least another of the two or more power input receptacles is abottom power input receptacle mounted on a bottom portion of theenclosure, wherein the bottom power input receptacle has a sameconnector type as the top power input receptacle; and two or more poweroutput receptacles on the enclosure, wherein the two or more poweroutput receptacles are electrically connected to the at least two powerinput receptacles wired in parallel so that the two or more power outputreceptacles are configured to receive power from any one of, or anycombination of, the at least two power input receptacles wired inparallel, wherein the two or more output receptacles are configured tosupply the power to at least one of the one or more computing devices,and wherein the two or more output receptacles have a differentreceptacle type than the top power input receptacle and the bottom powerinput receptacle; and one or more power cables each coupled in arespective one of the two or more power input receptacles on theenclosure, wherein at least one of the one or more power cables isconfigured to supply electrical power from an electrical power system tothe at least one of the one or more rack PDUs.
 2. The system of claim 1,wherein the at least one power cable feeds into the rack by way of apanel that is nearest to the top power input receptacle or nearest tothe bottom power input receptacle.
 3. The system of claim 1, wherein theat least one of the one or more rack PDUs comprises a phase matchdetection device, wherein the phase match detection device is configuredto determine whether respective phases of power fed to the at least oneof the power input receptacles and power fed to the at least another ofthe power input receptacles match within acceptable limits.
 4. Thesystem of claim 1, wherein the one or more power cables comprise atleast one power cable configured to supply a secondary feed through oneof the two or more power input receptacles of the at least one of therack PDUs while a primary feed is supplied through another power inputreceptacle of the two or more power input receptacles of the at leastone of the rack PDUs.
 5. The system of claim 1, wherein the one or morerack PDUs comprise two or more rack PDUs, wherein each of at least twoof the two or more rack PDUs comprises a respective top power inputreceptacle and a respective bottom power input receptacle.
 6. The systemof claim 1, wherein the one or more rack PDUs comprise two or more rackPDUs, wherein the one or more power cables comprise two or more powercables, wherein respective ones of the two or more power cables arecoupled in the top power input receptacles of respective ones of the twoor more rack PDUs or are coupled in the bottom power input receptaclesof respective ones of the two or more rack PDUs.
 7. The system of claim1, wherein the one or more rack PDUs comprise two or more rack PDUs,wherein the one or more power cables comprise two or more power cables,wherein at least one of the two or more power cables is coupled in thetop power input receptacle of one of the rack PDUs, and wherein anotherone of the two or more power cables is coupled in the bottom power inputreceptacle of another one of the rack PDUs.
 8. A rack power distributionunit (PDU), comprising: an enclosure; two or more power inputreceptacles mounted on the enclosure, wherein at least two of the two ormore power input receptacles are wired in parallel with one another,wherein: at least one of the two or more power input receptacles is atop power input receptacle mounted on a top portion of the enclosure;and at least another of the two or more power input receptacles is abottom power input receptacle mounted on a bottom portion of theenclosure, wherein the bottom power input receptacle has a sameconnector type as the top power input receptacle; and two or more poweroutput receptacles on the enclosure, wherein the two or more poweroutput receptacles are electrically connected to the at least two powerinput receptacles wired in parallel so that the two or more power outputreceptacles are configured to receive power from any one of, or anycombination of, the at least two power input receptacles wired inparallel, wherein the two or more power output receptacles areconfigured to supply the power to one or more electrical systems, andwherein the two or more output receptacles have a different receptacletype than the top power input receptacle and the bottom power inputreceptacle.
 9. The rack PDU of claim 8, wherein the bottom power inputreceptacle is located below the two or more power output receptacles andthe top power input receptacle is located above the two or more poweroutput receptacles.
 10. The rack PDU of claim 8, further comprising acircuit protection device coupled to each of the two or more power inputreceptacles, wherein each of the respective circuit protection devicesis configured to protect the one or more electrical systems that receiveelectrical power through a respective one of the two or more power inputreceptacles.
 11. The rack PDU of claim 8, wherein the rack PDU comprisesa phase match detection device coupled to the at least two of the powerinput receptacles, wherein the phase match detection device isconfigured to determine whether respective phases of power fed to the atleast one of the power input receptacles and the at least another of thepower input receptacles match within acceptable limits.
 12. The rack PDUof claim 11, wherein the phase match detection device comprises one ormore voltage comparators configured to compare voltages between linescoupled to the at least one of the power input receptacles and the atleast another of the power input receptacles.
 13. The rack PDU of claim8, further comprising one or more switching devices configured to openand close a connection between the at least two of the power inputreceptacles.
 14. The rack PDU of claim 8, further comprising a set oftwo or more power cables, wherein each power cable of the two or morepower cables comprises: a first end of the power cable configured tocouple in a respective one of the two or more power input receptacles;and a second end, wherein the second end of each of at least two of thetwo or more power cables is configured to couple with a differentupstream power distribution system.
 15. A method, comprising: providinga rack power distribution unit (PDU) with an enclosure and two or morerack PDU power input receptacles mounted on the enclosure, wherein thetwo or more rack PDU power input receptacles are wired in parallel withone another, wherein: at least one of the two or more rack PDU powerinput receptacles is a top power input receptacle mounted on a topportion of the enclosure; and at least another of the two or more rackPDU power input receptacles is a bottom power input receptacle mountedon a bottom portion of the enclosure, wherein the bottom power inputreceptacle has a same connector type as the top power input receptacle;the rack PDU comprises two or more power output receptacles on theenclosure, wherein the two or more power output receptacles areelectrically connected to the at least two power input receptacles wiredin parallel so that the two or more power output receptacles areconfigured to receive power from any one of, or any combination of, theat least two power input receptacles wired in parallel, wherein the twoor more output receptacles are configured to supply the power to one ormore electrical systems, and wherein the two or more output receptacleshave a different receptacle type than the top power input receptacle andthe bottom power input receptacle; and coupling a power cable to one ofthe two or more rack PDU power input receptacles that is nearest to alocation from which the power cable is being fed.
 16. The method ofclaim 15, wherein coupling the power cable to the one of the two or morerack PDU power input receptacles comprises establishing a secondary feedin the at least one of the two or more rack PDU power input receptacleswhile a primary feed is received in the at least another of the two ormore rack PDU power input receptacles of the rack PDU.
 17. The method ofclaim 15, further comprising verifying whether respective phases ofpower fed to the at least one of the two or more rack PDU power inputreceptacles match power fed to the at least another of the two or morerack PDU power input receptacles of the rack PDU.
 18. The method ofclaim 15, wherein coupling the power cable to one of the two or morerack PDU power input receptacles comprises: installing a power cable ina first one of the rack PDU power input receptacles, and, wherein themethod further comprises: after installing the power cable in the firstone of the rack PDU power input receptacles, removing another powercable from a second one of the two or more rack PDU power inputreceptacles.